Studies on the P-branch spectral lines of rovibrational transitions of diatomic system

An analytical formula is used to predict the accurate P-branch spectral lines of rovibrational transitions for diatomic systems. The formula is derived from elementary expression of molecular total energy by taking multiple spectral differences. It is not only reproduces the known experimental transition lines by using a group of fifteen known experimental transition data, but also predicts the accurate spectral lines that may not be available experimentally. The P-branch emission spectra of the (0,1), (0,2) and (0,3) bands of the B2 ∑ + → X2 ∑ + system in the 12C17O+ molecular ion are studied, and correct values of the unknown spectral lines up to J = 80.5 for each band are predicted using the formula.

Graphical abstractComparisons between experimental (“—”) P-branch emission spectra (Ref. [36]) and theoretical (“---”) spectra calculated using Eq. (1) for the (0,1) band of the B2∑+ → X2∑+ transition in the 12C17O+ molecular ion.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► This paper proposed an analytical formula based on the essential expression of molecular total energy by taking multiple spectral differences to predict the values of highlying unknown rovibrational transition P-branch spectral lines. ► This paper uses the formula to study the values of highlying unknown rovibrational transition P-branch spectral lines of the (0,1), (0,2) and (0,3) bands of the B2∑+ → X2∑+ system in the 12C17O+ molecular ion. ► The accurate results show that the analytical formula suggests a new efficient approach to generate or predict (for those diatomic molecular/ion electronic states whose experimental highlying spectra are unknown) spectral lines of diatomic electronic systems.